1. Field of the Invention
The present invention relates to a driver mental condition information system for informing of a driver's mental condition.
2. Description of the Related Background Art
Systems for providing the driver of a vehicle with information on a driver's mental condition such as sleepiness and fatigue are known (e.g., Japanese Patent Kokai No. 8-140949). In such a conventional driver mental condition information system, physiological data of a driver is detected, and a mental condition of the driver is then converted into a numerical value in accordance with the physiological data detected to compare the numerical value with a threshold value, thereby determining whether the mental condition of the driver has become too poor to assure the safe operation of a vehicle due to sleepiness, fatigue or the like. If the mental condition of the driver is determined to have become too poor, a warning is issued to the driver by means of a lamp or sound.
However, the conventional system has been designed to present only binary information that allowed a warning to be issued when the numerical value indicative of the mental condition of the driver exceeded the threshold value. Thus, there is a problem that the system is not able to precisely inform of the driver's mental condition that varied every moment.